Method and device for implementing virtual-switch

ABSTRACT

The present invention provides a method and a device for implementing a V-Switch. Through setting up a V-Switch correlation with respect to at least two VLAN tags, a DRE performs a V-Switch transmission on an Ethernet frame received according to the V-Switch correlation with respect to at least two VLAN tags. The invention can expand the number of V-Switch connections carried on a local link to 4096×4096, or even to 4096×4096×4096 . . . . Therefore, the problem of insufficient VLAN tag resources is solved, and the requirements for the scale of V-Switch technology is met. Moreover, a more effective V-Switch method is provided, the switching capability of V-Switch is improved, and the application scale of V-Switch technology is enlarged.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No. 12/014,170, filed on Jan. 15, 2008, which is a continuation of International Application No. PCT/CN2006/001290, filed on Jun. 12, 2006. The International Application claims priority to Chinese Patent Application No. 200510083968.6, filed on Jul. 15, 2005. The afore-mentioned patent applications are hereby incorporated by reference in their entireties.

FIELD OF THE INVENTION

The present invention relates to the technical field of network communications, in particular, to a method and a device for implementing a Virtual-Switch (V-Switch).

BACKGROUND OF THE INVENTION

As the scale of Internet becomes larger, various network services spring up one after another, and advanced multimedia systems emerge in endlessly. Because real-time services are sensitive to the features of network, such as transmission delay and time delay jitter, when File Transfer Protocol (FTP) service with a high burst or Hyper Text Transport Protocol (HTTP) service having an image file occurs, the real-time service will be influenced greatly. Moreover, the multimedia service occupies substantial bandwidth, thus the key service to be guaranteed by the network may not be transmitted reliably. Therefore, various Quality of Service (QoS) technologies emerge as required. Internet Engineering Task Force (IETF) has proposed many service models and mechanisms to meet QoS requirements.

Various portal-based applications, services and broadband multimedia services have become important contents of broadband operators, including services provided to common residential users, such as Video/Audio streams, Video On Demand (VOD), Video Multicast, the multimedia interaction, network games requiring a high bandwidth and services provided to commercial users, such as the video conference, the remote education, Virtual Private Network (VPN), Data Private Line with guaranteed QoS, and Internet Protocol Hotel (IPHotel).

The Ethernet technology and the End-To-End Ethernet technology enjoy a high recognition among the Operators and enterprise users. The Ethernet technology has become one of the main technologies for implementing Triple Play and Metropolitan Area Network in the future. Therefore, the Ethernet service may have a cheerful prospect in the future market.

At present, various VPN or Virtual Private Dial-up Network (VPDN) private line solutions, such as V-Switch, Generic Routing Encapsulation (GRE), Layer 2 Tunneling Protocol (L2TP), Multiple Protocols Label Switch (MPLS), have been put forward for these commercial users.

The Intelligent V-Switch (IVS) technology is mainly used for constructing a stable, practical, economic, and carrier-level Metropolitan Area Ethernet. Therefore, telecommunication-level functions with guaranteed QoS and network security protection, such as network maintenance and management, may be implemented. Further, the IVS technology provides core service management capabilities, such as number-based user management, certain mobility, open service and centralized charging management, and the IVS technology also provides services such as intelligent layer 2 flow scheduling, Local Area Network (LAN) private line, and IP flow planning. The occurrence of IVS improve the pure layer-2 capability in current network and plays an important role in the construction of Metropolitan Area Networks in new era.

The V-Switch architecture has a Ethernet VLAN switching and scheduling function, flexible measures for scheduling, setting up and adjusting services, an abundant and extensible layer-2 service provision capability, and Operation, Administration And Maintenance (OAM) tools and information. The logic layers and function model of the V-Switch system are as shown in FIG. 1.

In FIG. 1, the V-Switch system is divided into three layers: V-Switch service control layer, V-Switch connection control layer and V-Switch bearer layer.

The V-Switch connection control layer maintains switching resources in a Data Retransmission Entity (DRE), such as equipment, ports, links and VLAN tags, receives a V-Switch setup request from a Service Control Register (SCR) of the service layer V-Switch, selects a traffic flow path for the V-Switch connection, allocates a bandwidth and Virtual Local Area Network (VLAN) tags, and transmits the control information to the DRE equipment through which the traffic flow passes.

The DRE lies in the V-Switch bearer layer. The DRE forwards the traffic flow in Ethernet frame format according to a VLAN switching table configured by the V-Switch connection control layer.

The contents of the VLAN switching table are as shown in Table 1.

TABLE 1 Parameter Parameter Description port 1 Traffic flow forwarding port 1 , such as GE 1/0/0 vlan id 1 VLAN ID carried in traffic flow on Port 1 in the Ethernet frame format port 2 Traffic flow forwarding port 2, such as GE 1/0/1 vlan id 2 VLAN ID carried in traffic flow on Port 2 in the Ethernet frame format Bandwidth Bandwidth limitation for traffic flow .1 Upstream Maximum bandwidth of upstream traffic flow Maximum (received at port 1, and sent from port 2) Bandwidth .2 Downstream Maximum bandwidth of downstream traffic flow Maximum (received at port 2, and sent from port 1) Bandwidth QoS QoS parameter requirement for traffic flow Parameter .1 Delay .2 Delay Jitter .3 Packet Loss Ratio

The traffic flow is forwarded by the DRE based on the VLAN switching table. The process in which the DRE forwards the traffic flow data according to the VLAN switching table is implemented as follows.

When an Ethernet frame of vlan id 1 received at port 1 is sent to port 2, vlan id 1 is swapped into vlan id 2. When an Ethernet frame of vlan id 2 received at port 2 is sent to port 1, vlan id 2 is swapped into vlan id 1.

Through the above forwarding, a VLAN virtual channel may be set up in the network. The virtual channel may be described as: (equipment 1, port 1, vlan id 1)-(equipment 1, port 2, vlan id 2)-(equipment 2, port 3, vlan id 2)-(equipment 2, port 1, vlan id 3) . . . .

The conventional Ethernet switch can only support the transparent transmission of 4096 VLAN tags globally. The V-Switch technology implements the switching between different VLAN IDs and localizes the VLAN ID, so that the VLAN ID has a local meaning.

Although the method for implementing the switching between different VLAN IDs according to a current V-Switch technology can alleviate the problem of insufficient VLAN tag resources, the problem of insufficient VLAN tag resources cannot be solved completely. The number of VLAN tags on each local link is still limited to 4096, and the number of V-Switch connections carried on each local link cannot be larger than 4096. Therefore, the application scale of V-Switch technology is limited.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a method and a device for implementing a V-Switch, so that the number of V-Switch connections carried on each local link can break through the limitation by using at least two VLAN tags. Hence, the switching capability of the V-Switch technology may be improved, and the application scale of V-Switch technology may be enlarged.

The invention provides a method for implementing a V-Switch, includes: setting up a V-Switch correlation with respect to at least two VLAN tags; and performing, by a DRE, a V-Switch transmission on a data frame received according to the V-Switch correlation.

The at least two VLAN tags include an outer VLAN tag and an inner VLAN tag, and the inner VLAN tag has at least one VLAN tag.

Setting up the V-Switch correlation includes:

setting up a correlation with respect to a first port, a first port VLAN tag and a second port, a second port outer VLAN tag, a second port inner VLAN tag.

The method further includes: performing, by the DRE, a QinQ (VLAN Stack) encapsulation on an Ethernet frame encapsulated with VLAN protocol of the first port VLAN tag received from the first port according to the second port inner VLAN tag and the second port outer VLAN tag in the correlation, and transmitting an encapsulated Ethernet frame via the second port; and performing, by the DRE, a VLAN protocol encapsulation on an Ethernet frame encapsulated with QinQ of the second port inner VLAN tag and the second port outer VLAN tag received from the second port according to the first port VLAN tag in the correlation, and transmitting an encapsulated Ethernet frame via the first port

The method further includes:

setting up a correlation with respect to a first port, a first port outer VLAN tag, a first port inner VLAN tag and a second port, a second port outer VLAN tag, a second port inner VLAN tag.

The method further includes:

performing, by the DRE, a QinQ encapsulation on an Ethernet frame encapsulated with QinQ of the first port outer VLAN tag and the first port inner VLAN tag received from the first port according to the second port inner VLAN tag and the second port outer VLAN tag in the correlation, and transmitting an encapsulated Ethernet frame via the second port; and performing, by the DRE, the QinQ encapsulation on an Ethernet frame encapsulated with QinQ of the second port inner VLAN tag and the second port outer VLAN tag received from the second port according to the first port inner VLAN tag and the first port outer VLAN tag in the correlation, and transmitting an encapsulated Ethernet frame via the first port.

The correlation is set in a VLAN switching table.

The method further includes: adding an inner VLAN tag field to the VLAN switching table;

when an inner VLAN tag corresponding to one port in one record of the VLAN switching table includes an invalid VLAN ID and an inner VLAN tag corresponding to the other port includes a valid VLAN ID, storing the correlation with respect to the first port, the first port outer VLAN tag and the second port, the second port outer VLAN tag, the second port inner VLAN tag in the record; when the inner VLAN tags corresponding to two ports in one record of the VLAN switching table are both valid VLAN IDs, storing the correlation with respect to the first port, the first port outer VLAN tag, the first port inner VLAN tag and the second port, the second port outer VLAN tag, the second port inner VLAN tag in the record; and when the inner VLAN tags corresponding to two ports in one record of the VLAN switching table are both invalid VLAN IDs, storing the correlation with respect to the first port, the first port outer VLAN tag and the second port, the second port outer VLAN tag in the record.

The method further includes:

adding a switching mode type field and an inner VLAN tag field to the VLAN switching table; when a switching mode type in one record of the VLAN switching table is a first predetermined value, storing the correlation with respect to the first port, the first port outer VLAN tag and the second port, the second port outer VLAN tag, the second port inner VLAN tag in the record; when the switching mode type in one record of the VLAN switching table is a second predetermined value, storing the correlation with respect to the first port, the first port outer VLAN tag, the first port inner VLAN tag and the second port, the second port outer VLAN tag and the second port inner VLAN tag in the record; and when the switching mode type in one record of the VLAN switching table is a third predetermined value, storing the correlation with respect to the first port, the first port outer VLAN tag and the second port, the second port outer VLAN tag in the record.

The invention further provides a device for implementing a V-Switch, including:

a storage module, adapted to store a V-Switch correlation with respect to at least two VLAN tags; and a forwarding module, adapted to transmit an Ethernet frame received according to the V-Switch correlation stored in the storage module.

It can be seen from the above descriptions, through setting up a V-Switch correlation with respect to at least two VLAN tags, the DRE can implement a new V-Switch transmission for an Ethernet frame according to the correlation. For example, the V-Switch transmission for an Ethernet frame encapsulated with VLAN and an Ethernet frame encapsulated with QinQ is implemented, and the V-Switch transmission for an Ethernet frame encapsulated with QinQ and another Ethernet frame encapsulated with QinQ is implemented, thus it is avoided that the number of local VLAN tags is limited to 4096. When the two VLAN tags are used, the number of V-Switch connections carried on a local link is extended to 4096×4096, and when three- or more-layer VLAN tags are used, the number of V-Switch connections carried on a local link is extended to 4096×4096×4096 . . . . Thus, the problem of insufficient VLAN tag resources is effectively solved, and the requirement for the application scale of the V-Switch technology is met. The invention implements the V-Switch method, and the switching capability of the V-Switch technology is improved, and the application scale of the V-Switch technology is enlarged.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of the logic layers and function models of a V-Switch system; and

FIG. 2 is a schematic diagram of a V-Switch device according to one embodiment of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The invention provides a method and a device for implementing a V-Switch. According to the invention, a V-Switch correlation with respect to at least two VLAN tags is set up, a DRE can perform a V-Switch transmission on a received Ethernet frame according to the V-Switch correlation with respect to the at least two VLAN tags.

To make the principles, features and advantages of the invention more apparent, the embodiments of the invention will now be further described by taking two specific methods for V-Switch as examples.

Embodiment 1

In the method for implementing the V-Switch according to the first embodiment of the invention, only one side in the correlation includes at least two VLAN tags.

First of all, a correlation with respect to Port1, Port1 VLAN tag vlan1 and Port2, Port2 outer VLAN tag Ovlan2, Port2 inner VLAN tag Ivlan2, is set up. Thus, when a DRE receives an Ethernet frame encapsulated with one VLAN tag vlan1 from Port1, the DRE converts the Ethernet frame into an Ethernet frame encapsulated with Ovlan2 and Ivlan2, then the DRE forwards the frame encapsulated with Ovlan2 as the outer VLAN tag and Ivlan2 as the inner VLAN tag through Port2. When the DRE receives the Ethernet frame encapsulated with Ovlan2 as the outer VLAN tag and Ivlan2 as the inner VLAN tag from Port2, the DRE converts the Ethernet frame into an Ethernet frame encapsulated with vlant then forwards the frame encapsulated with vlan1 through Port1. In this embodiment, in order to solve the problem that the number of local VLAN tags is limited to 4096, the number of V-Switch connections carried on each local link may be extended to 4096×4096 through the two VLAN tags. When the inner VLAN tag includes three- or more-VLAN tags, the invention can extend the number of V-Switch connections carried on each local link to 4096×4096×4096 . . . . Thus, the number of V-Switch connections carried on each link may be extended greatly, the problem of insufficient VLAN tag resources can be effectively solved, and the requirements for the application scale of V-Switch technology can be met.

Embodiment 2

In the method for implementing the V-Switch according to the second embodiment of the invention, both sides in the correlation include at least two VLAN tags.

First of all, a correlation with respect to Port1, Port1 Outer VLAN tag Ovlan1, Port1 Inner VLAN tag Ivlan1 and Port2, Port2 Outer VLAN tag Ovlan2, Port2 Inner VLAN tag Ivlan2, is set up. Thus, when a DRE receives an Ethernet frame encapsulated with Ovlan1 and Ivlan1 from Port1, the DRE converts the Ethernet frame into an Ethernet frame encapsulated with Ovlan2 and Ivlan2, and then forwards the Ethernet frame encapsulated with Ovlan2 and Ivlan2. When the DRE receives the Ethernet frame encapsulated with Ovlan2 and Ivlan2 from Port2, the DRE converts frame encapsulated with the Ovlan2 and Ivlan2 in a frame with encapsulated Ovlan1 and Ivlan1, and then forwards the Ethernet frame encapsulated with Ovlan1 and Ivlan1 to Port 1. Similarly, this embodiment also solves the problem that the number of local VLAN tags is limited to 4096, and the number of V-Switch connections carried on each local link may be extended to 4096×4096 by the two VLAN tags. When the number of inner VLAN tags is three or more, the invention can extend the number of V-Switch connections carried on each local link to 4096×4096×4096 . . . . Thus, the number of V-Switch connections carried on each link may be extended greatly, the problem of insufficient VLAN tag resources can be effectively solved, and the requirements for the application scale of the V-Switch technology can be met.

The V-Switch correlation with respect to at least two VLAN tags in the above Embodiments may be implemented by extending the VLAN tag switching table in the DRE.

When the inner VLAN tag only includes one inner VLAN tag, the extended VLAN tag switching table is as shown in Table 2.

TABLE 2 Parameter Parameter Description 1 port 1 Traffic flow forwarding port 1, such as GE 1/0/0 2 vlan id 1 The VLAN ID carried in Ethernet frame of traffic flow on Port 1 2.1 vlan id 1′ An invalid or illegal value of vlan id 1′ (extension) indicates a common 802.1Q encapsulation with only one VLAN Tag encapsulated; and a valid value indicates a QinQ encapsulation, and the valid value is the inner VLAN (vlan id 1 is the outer VLAN) 3 port 2 Traffic flow forwarding port 2, such as GE 1/0/1 4 vlan id 2 The VLAN ID encapsulated in Ethernet frame of traffic flow on Port 2 4.1 vlan id 2′ An invalid or illegal value of vlan id 2′ (extension) indicates a common 802.1Q encapsulation with only one VLAN Tag encapsulated; and a valid value indicates a QinQ encapsulation, and the valid value is the inner VLAN (vlan id 2 is the outer VLAN) 5 Bandwidth Bandwidth limitation of traffic flow 5.1 Upstream The maximum bandwidth of upstream traffic Maximum flow (received from port 1, and sent Bandwidth through port 2) 5.2 Downstream The maximum bandwidth of downstream Maximum traffic flow (received from port 2, and Bandwidth sent through port 1) 6 QoS QoS parameter requirement for traffic flow Parameter 6.1 Delay 6.2 Delay Jitter 6.3 Packet Loss Ratio

In Table 2, when vlan id 1′ corresponding to port 1 is an invalid VLAN ID and vlan id 2′ corresponding to Port2 is a valid VLAN ID, or when vlan id 1′ corresponding to port 1 is a valid VLAN ID and vlan id 2′ corresponding to Port2 is an invalid VLAN ID, or when vlan id 1′ corresponding to port 1 is a valid VLAN ID and vlan id 2′ corresponding to Port2 is also a valid VLAN ID, it is indicated that the DRE needs to perform the V-Switch transmission of the invention on an Ethernet frame received according to the table item.

When vlan id 1′ corresponding to port 1 is an invalid VLAN ID and vlan id 2′ corresponding to Port2 is an invalid VLAN ID, it is indicated that the DRE needs to perform “Port+VLAN” V-Switch transmission in the prior art on a received Ethernet frame according to the table item.

The two methods for implementing the V-Switch according to the invention may be implemented by the VLAN Stack technology.

The VLAN Stack technology is also referred to as QinQ (VLAN Stack), which is a picturesque name of the tunneling protocol based on encapsulation of 802.1Q. The core concept lies in that: the inner VLAN tag of the user is encapsulated with the outer VLAN tag, and a packet carrying the two tags passes through the backbone network of the service provider, and the outer VLAN tag is deleted when the packet exits the network of the service provider. Therefore, a simple layer 2 VPN tunneling may be provided to the user.

When the correlation in the invention is set according to Table 2, the DRE implements the V-Switch transmission using the VLAN Stack technology as follows.

After the DRE receives a packet from port 1, the DRE first needs to determine the items in the VLAN switching table corresponding to the packet; then, the DRE determines whether the values of vlan id Vand vlan id 2′ in the table are valid.

If vlan id 1′ in the table is valid and vlan id 2′ is invalid, the packet received by the DRE will be an Ethernet frame encapsulated with the QinQ, in other words, the packet received by the DRE is an Ethernet frame encapsulated with the QinQ and having an outer VLAN tag of vlan id 1 and an inner VLAN tag of vlan id 1′. The DRE needs to convert the Ethernet frame encapsulated with vlan id 1 and vlan id 1′ into an Ethernet frame encapsulated with vlan id 2, and send the Ethernet frame encapsulated with vlan id 2 via Port2, so that the V-Switch transmission may be implemented between an Ethernet frame encapsulated with QinQ and an Ethernet frame encapsulated with 802.1Q.

If vlan id 2′ in the table is valid and vlan id 1′ is invalid, the packet received by the DRE will be an Ethernet frame encapsulated with 802.1Q and having a vlan tag of vlan id 1, and the DRE needs to convert the Ethernet frame encapsulated with vlan id 1 into an Ethernet frame encapsulated with vlan id 2 and vlan id 2′, in other words, the Ethernet frame is encapsulated with QinQ and has an outer VLAN tag of vlan id 2 and an inner VLAN tag of vlan id 2′. The DRE sends the converted Ethernet frame via Port2, so that the V-Switch transmission can be implemented between an Ethernet frame encapsulated with 802.1Q and an Ethernet frame encapsulated with QinQ.

If vlan id 1′ and vlan id 2′ in the table are both valid, the packet received by the DRE is an Ethernet frame encapsulated with QinQ and having vlan tags of vlan id 1 and vlan id 1′, in other words, the Ethernet frame is encapsulated with QinQ and has an outer VLAN of vlan id 1 and an inner VLAN of vlan id 1′, and the DRE needs to convert the Ethernet frame encapsulated with vlan id 1 and vlan id 1′ into an Ethernet frame encapsulated with an outer VLAN of vlan id 2 and an inner VLAN of vlan id 2′, and send the converted Ethernet frame via Port2, so that the V-Switch transmission is implemented between an Ethernet frame encapsulated with QinQ and an Ethernet frame encapsulated with QinQ.

If vlan id 1′ and vlan id 2′ in the table are both invalid, the packet received by the DRE will be an Ethernet frame encapsulated with 802.1Q and having a Vlan tag of vlan id 1, and the DRE needs to implement the V-Switch transmission for the packet according to “Port+VLAN” V-Switch method in the prior art.

The invention may implement the correlation by other method for expanding the VLAN switching table. For example, in addition to the field vlan id 1′ and the field vlan id 2′, a switching mode type field may be added to the VLAN switching table. The VLAN switching mode employed by the DRE may be indicated according to different values of the switching mode type field. For example, when the value of the switching mode type field is a first predetermined value, the DRE can perform the V-Switch transmission on a packet with the V-switch method in which only one side in the correlation includes the inner VLAN tag. When the value of the switching mode type field is a second predetermined value, the DRE may perform the V-switch transmission on a packet with the V-switch method in which both sides in the correlation include an inner VLAN tag. When the value of the switching mode type filed is the third predetermined value, the DRE may perform the V-switch transmission on a packet with the “Port+VLAN” V-switch method in the prior art.

The V-Switch device according to the invention is as shown in FIG. 2.

In FIG. 2, the V-Switch device includes a storage module and a switching module.

The storage module is adapted to store a V-Switch correlation. Here, the V-Switch correlation includes: a V-Switch correlation with respect to at least two VLAN tags and a correlation with respect to Port1, Port1 VLAN tag 1 and Port2, Port2 VLAN tag 2. The V-Switch correlation with respect to at least two VLAN tags includes: a correlation with respect to Port1, Port1 VLAN tag 1 and Port2, Port2 outer VLAN tag 2, Port2 inner VLAN tag 2; and a correlation with respect to Port1, Port1 outer VLAN tag 1, Port1 inner VLAN tag 1 and Port2, Port2 outer VLAN tag 2, Port2 inner VLAN tag 2. These correlations may be stored in the form of a VLAN switching table.

The switching module is adapted to receive an Ethernet frame, determine an item in the VLAN switching table corresponding to the Ethernet frame and determine the switching mode for the Ethernet frame according to the contents in the item, and then send the packet according to the switching mode for the Ethernet frame. For example, the V-Switch transmission is performed with the method for the V-Switch in which only one side in the correlation includes at least two VLAN tags, or the V-Switch transmission is performed with the method for the V-Switch in which both sides in the correlation include at least two VLAN tags, or the V-Switch transmission is performed with “Port+VLAN” method in the prior art. The method of the switching module to perform the V-Switch transmission on the packet is similar to that in the above descriptions, and repeat descriptions thereof are omitted.

The device for implementing the V-Switch according to the invention includes an intermediate DRE in a V-Switch domain.

Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications and variations may be made without departing from the scope of the invention as defined by the appended claims and their equivalents. 

1. A method for implementing a Virtual-Switch (V-Switch), comprising: setting up a V-Switch correlation with respect to at least two Virtual Local Area Network (VLAN) tags; receiving a data frame; and performing, by a Data Retransmission Entity (DRE), a V-Switch transmission on the data frame received according to the V-Switch correlation with respect to the at least two VLAN tags.
 2. The method for implementing the V-Switch according to claim 1, wherein, the at least two VLAN tags comprise an outer VLAN tag and an inner VLAN tag, and the inner VLAN tag comprises at least a one-layer VLAN tag.
 3. The method for implementing the V-Switch according to claim 2, wherein, the V-Switch correlation is a correlation with respect to a first port, a first port VLAN tag and a second port, a second port outer VLAN tag, and a second port inner VLAN tag.
 4. The method for implementing the V-Switch according to claim 3, further comprising: performing, by the DRE, a VLAN stack (QinQ) encapsulation on a VLAN protocol encapsulated Ethernet frame having the first port VLAN tag and received from the first port according to the second port inner VLAN tag and the second port outer VLAN tag in the correlation, and transmitting an encapsulated Ethernet frame via the second port; and performing, by the DRE, a VLAN protocol encapsulation on a QinQ encapsulated Ethernet frame having the second port inner VLAN tag and the second port outer VLAN tag and received from the second port according to the first port VLAN tag in the correlation, and transmitting a VLAN protocol encapsulated Ethernet frame via the first port.
 5. The method for implementing the V-Switch according to claim 2, wherein, the V-switch correlation is a correlation with respect to a first port, a first port outer VLAN tag, a first port inner VLAN tag and a second port, a second port outer VLAN tag, and a second port inner VLAN tag.
 6. The method for implementing the V-Switch according to claim 5, comprising: performing, by the DRE, a QinQ encapsulation on an Ethernet frame according to the second port inner VLAN tag and the second port outer VLAN tag in the correlation, wherein the Ethernet frame is encapsulated with QinQ of the first port outer VLAN tag and the first port inner VLAN tag and received from the first port, and transmitting an encapsulated Ethernet frame via the second port; and performing, by the DRE, a QinQ encapsulation on an Ethernet frame according to the first port inner VLAN tag and the first port outer VLAN tag in the correlation, wherein the Ethernet frame is encapsulated with QinQ of the second port inner VLAN tag and the second port outer VLAN tag and received from the second port, and transmitting a QinQ encapsulated Ethernet frame via the first port.
 7. The method for implementing the V-Switch according to claim 2, wherein, the correlation is set in a VLAN switching table.
 8. The method for implementing the V-Switch according to claim 7, wherein: an inner VLAN tag field is configured in the VLAN switching table; when an inner VLAN tag corresponding to one port in a first record of the VLAN switching table is an invalid VLAN ID and an inner VLAN tag corresponding to the other port is a valid VLAN ID, information stored in the first record is the correlation with respect to a first port, a first port outer VLAN tag and a second port, a second port outer VLAN tag, and a second port inner VLAN tag; when the inner VLAN tags corresponding to two ports in a second record of the VLAN switching table are both valid VLAN IDs, information stored in the second record is the correlation with respect to the first port, the first port outer VLAN tag, the first port inner VLAN tag and the second port, the second port outer VLAN tag, and the second port inner VLAN tag; and when the inner VLAN tags corresponding to two ports in a third record of the VLAN switching table are both invalid VLAN IDs, information stored in the third record is the correlation with respect to the first port, the first port outer VLAN tag and the second port, and the second port outer VLAN tag.
 9. The method for implementing the V-Switch according to claim 7, wherein: a switching mode type field and an inner VLAN tag field are configured in the VLAN switching table; when a switching mode type in a first record of the VLAN switching table is a first predetermined value, information stored in the first record is the correlation with respect to a first port, a first port outer VLAN tag and a second port, a second port outer VLAN tag, and a second port inner VLAN tag; when a switching mode type in a second record of the VLAN switching table is a second predetermined value, information stored in the second record is the correlation with respect to the first port, the first port outer VLAN tag, the first port inner VLAN tag and the second port, the second port outer VLAN tag and the second port inner VLAN tag; and when a switching mode type in a third record of the VLAN switching table is a third predetermined value, information stored in the third record is the correlation with respect to the first port, the first port outer VLAN tag and the second port, and the second port outer VLAN tag.
 10. The method for implementing the V-Switch according to claim 3, further comprising: converting, by the DRE, a VLAN protocol encapsulated Ethernet frame having the first port VLAN tag and received from the first port to an encapsulated Ethernet frame which encapsulated with QinQ of the second port inner VLAN tag and the second port outer VLAN tag according to the correlation, and transmitting the encapsulated Ethernet frame via the second port; or converting, by the DRE, an encapsulated Ethernet frame having the second port inner VLAN tag and the second port outer VLAN tag and received from the second port to a VLAN protocol encapsulated Ethernet frame having the first port VLAN tag according to the correlation, and transmitting the VLAN protocol encapsulated Ethernet frame via the first port.
 11. The method for implementing the V-Switch according to claim 5, comprising: converting, by the DRE, an first encapsulated Ethernet frame to a second encapsulated Ethernet frame according to the correlation, wherein the first encapsulated Ethernet frame is encapsulated with QinQ of the first port outer VLAN tag and the first port inner VLAN tag and received from the first port, the second encapsulated Ethernet frame is encapsulated with QinQ of the second port inner VLAN tag and the second port outer VLAN tag, and transmitting the second encapsulated Ethernet frame which has been converted via the second port; or converting, by the DRE, a third encapsulated Ethernet frame to a fourth encapsulated Ethernet frame according to the correlation, wherein the third encapsulated Ethernet frame is encapsulated with QinQ of the second port inner VLAN tag and the second port outer VLAN tag and received from the second port, the fourth encapsulated Ethernet frame is encapsulated with QinQ of the first port inner VLAN tag and the first port outer VLAN tag, and transmitting the QinQ encapsulated Ethernet frame which has been converted via the first port.
 12. The method for implementing the V-Switch according to claim 7, wherein: an inner VLAN tag field is configured in the VLAN switching table; when an inner VLAN tag corresponding to one port in one record of the VLAN switching table is an invalid VLAN ID and an inner VLAN tag corresponding to the other port is a valid VLAN ID, the method comprises: converting, by the DRE, a VLAN protocol encapsulated Ethernet frame having a first port VLAN tag and received from a first port to an encapsulated Ethernet frame which is encapsulated with QinQ of the a second port inner VLAN tag and a second port outer VLAN tag according to the correlation, and transmitting the encapsulated Ethernet frame which has been converted via a second port; or converting, by the DRE, an encapsulated Ethernet frame which is encapsulated with QinQ of the second port inner VLAN tag and the second port outer VLAN tag and received from the second port to a VLAN protocol encapsulated Ethernet frame having the first port VLAN tag according to the correlation, and transmitting the VLAN protocol encapsulated Ethernet frame which has been converted via the first port.
 13. The method for implementing the V-Switch according to claim 7, wherein: an inner VLAN tag field is configured in the VLAN switching table; when inner VLAN tags corresponding to both ports in one record of the VLAN switching table are invalid VLAN IDs, the method comprises: converting, by the DRE, an encapsulated Ethernet frame which is encapsulated with QinQ of a first port outer VLAN tag and a first port inner VLAN tag and received from a first port to an encapsulated Ethernet frame which is encapsulated with QinQ of a second port inner VLAN tag and a second port outer VLAN tag according to the correlation, and transmitting the encapsulated Ethernet frame which has been converted via a second port; or converting, by the DRE, an encapsulated Ethernet frame which is encapsulated with QinQ of the second port inner VLAN tag and the second port outer VLAN tag and received from the second port to an encapsulated Ethernet frame which is encapsulated with QinQ of the first port inner VLAN tag and the first port outer VLAN tag according to the correlation, and transmitting the encapsulated Ethernet frame which has been converted via the first port.
 14. The method for implementing the V-Switch according to claim 7, wherein: a switching mode type field and an inner VLAN tag field are configured in the VLAN switching table; when a switching mode type in one record of the VLAN switching table is a first predetermined value, information stored in the record is the correlation with respect to a first port, a first port outer VLAN tag and a second port, a second port outer VLAN tag, and a second port inner VLAN tag; and the method further comprises: converting, by the DRE, a VLAN protocol encapsulated Ethernet frame having the first port outer VLAN tag and received from the first port to an encapsulated Ethernet frame which is encapsulated with QinQ of the second port inner VLAN tag and the second port outer VLAN tag according to the correlation, and transmitting the encapsulated Ethernet frame which has been converted via the second port; or converting, by the DRE, a encapsulated Ethernet frame which is encapsulated with QinQ of the second port inner VLAN tag and the second port outer VLAN tag and received from the second port to a VLAN protocol encapsulated Ethernet frame having the first port VLAN tag according to the correlation, and transmitting the VLAN protocol encapsulated Ethernet frame which has been converted via the first port.
 15. The method for implementing the V-Switch according to claim 7, wherein: a switching mode type field and an inner VLAN tag field are configured in the VLAN switching table; when the switching mode type in one record of the VLAN switching table is a second predetermined value, information stored in the record is the correlation with respect to a first port, a first port outer VLAN tag, a first port inner VLAN tag and a second port, a second port outer VLAN tag and a second port inner VLAN tag; converting, by the DRE, an encapsulated Ethernet frame which is encapsulated with QinQ of the first port outer VLAN tag and the first port inner VLAN tag and received from the first port to an encapsulated Ethernet frame which is encapsulated with QinQ of the second port inner VLAN tag and the second port outer VLAN tag according to the correlation, and transmitting the encapsulated Ethernet frame which has been converted via the second port; or converting, by the DRE, a QinQ encapsulated Ethernet frame having the second port inner VLAN tag and the second port outer VLAN tag and received from the second port to a QinQ encapsulated Ethernet frame having the first port inner VLAN tag and the first port outer VLAN tag according to the correlation, and transmitting the QinQ encapsulated Ethernet frame which has been converted via the first port.
 16. A device for implementing a V-Switch, comprising: a storage module, configured to store a V-Switch correlation with respect to at least two VLAN tags; a forwarding module, configured to transmit an Ethernet frame received according to the V-Switch correlation stored in the storage module.
 17. The device according to claim 16, wherein, the at least two VLAN tags comprise an outer VLAN tag and an inner VLAN tag, and the inner VLAN tag comprises at least a one-layer VLAN tag.
 18. The device according to claim 16, wherein, the V-Switch correlation is a correlation with respect to a first port, a first port VLAN tag and a second port, a second port outer VLAN tag, and a second port inner VLAN tag.
 19. The device according to claim 18, wherein, transmitting an Ethernet frame received according to the V-Switch correlation stored in the storage module comprises: converting, by the DRE, a VLAN protocol encapsulated Ethernet frame having the first port VLAN tag and received from the first port to an encapsulated Ethernet frame which is encapsulated with QinQ of the second port inner VLAN tag and the second port outer VLAN tag according to the correlation, and transmitting the encapsulated Ethernet frame which has been converted via the second port; or converting, by the DRE, an encapsulated Ethernet frame which is encapsulated with QinQ of the second port inner VLAN tag and the second port outer VLAN tag and received from the second port to a VLAN protocol encapsulated Ethernet frame having the first port VLAN tag according to the correlation, and transmitting the VLAN protocol encapsulated Ethernet frame which has been converted via the first port.
 20. The device according to claim 17, wherein, the V-switch correlation is a correlation with respect to a first port, a first port outer VLAN tag, a first port inner VLAN tag and a second port, a second port outer VLAN tag, a second port inner VLAN tag.
 21. The device according to claim 20, wherein, transmitting an Ethernet frame received according to the V-Switch correlation stored in the storage module comprises: converting, by the DRE, an encapsulated Ethernet frame which is encapsulated with QinQ of the first port outer VLAN tag and the first port inner VLAN tag and received from the first port to an encapsulated Ethernet frame which is encapsulated with QinQ of the second port inner VLAN tag and the second port outer VLAN tag according to the correlation, and transmitting the encapsulated Ethernet frame which has been converted via the second port; or converting, by the DRE, an encapsulated Ethernet frame which is encapsulated with QinQ of the second port inner VLAN tag and the second port outer VLAN tag and received from the second port to an encapsulated Ethernet frame which is encapsulated with QinQ of the first port inner VLAN tag and the first port outer VLAN tag according to the correlation, and transmitting the encapsulated Ethernet frame which has been converted via the first port.
 22. The device according to claim 17, wherein, the correlation is configured in the VLAN switch table.
 23. The device according to claim 22, wherein, an inner VLAN tag field is configured in the VLAN switching table; when an inner VLAN tag corresponding to one port in a first record of the VLAN switching table is an invalid VLAN ID and an inner VLAN tag corresponding to the other port is a valid VLAN ID, information stored in the first record is the correlation with respect to the first port, the first port outer VLAN tag and the second port, the second port outer VLAN tag, the second port inner VLAN tag; when the inner VLAN tags corresponding to two ports in a second record of the VLAN switching table are both valid VLAN IDs, information stored in the second record is the correlation with respect to the first port, the first port outer VLAN tag, the first port inner VLAN tag and the second port, the second port outer VLAN tag, the second port inner VLAN tag; and when the inner VLAN tags corresponding to two ports in a third record of the VLAN switching table are both invalid VLAN IDs, information stored in the third record is the correlation with respect to the first port, the first port outer VLAN tag and the second port, the second port outer VLAN tag.
 24. The device according to claim 22, wherein, a switching mode type field and an inner VLAN tag field are configured in the VLAN switching table; when a switching mode type in a first record of the VLAN switching table is a first predetermined value, information stored in the first record is the correlation with respect to the first port, the first port outer VLAN tag and the second port, the second port outer VLAN tag, the second port inner VLAN tag; when a switching mode type in a second record of the VLAN switching table is a second predetermined value, information stored in the second record is the correlation with respect to the first port, the first port outer VLAN tag, the first port inner VLAN tag and the second port, the second port outer VLAN tag and the second port inner VLAN tag; and when a switching mode type in a third record of the VLAN switching table is a third predetermined value, information stored in the third record is the correlation with respect to the first port, the first port outer VLAN tag and the second port, the second port outer VLAN tag. 